Special character causing problems in CF8 XML output

I am sending a query result (query in CF8; data in MS SQL Server 2005) to an XML output (using the and #toString(outputname)#
tags), using CF8. When the output (in SQL Server as nvarchar) contains special characters like "-40° to 70°C" the ° symbol causes the error;
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The XML page cannot be displayed
Cannot view XML input using XSL style sheet. Please correct the error and then click the Refresh button, or try again later.
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An invalid character was found in text content. Error processing resource 'http://localhost/ABSwwwroot/ArchboldData/toXML.c...

-40
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How can I get this type of value to display properly?